Electric switch devices



July 2, 1957 1. w. cox 2,798,130

ELECTRIC SWITCH DEVICES Filed May 22, 1955 States ELECTRIC SWITCH DEVICES Irvin W. Cox, West Allis, Wis., assignor to Cutler-Harnrner, Inc, Milwaukee, Wis., a corporation of Delaware This invention relates to electric switch devices and particularly switch devices which are responsive to pressure and/ or temperature.

A primary object of the invention is to provide electric switch devices of the character described which will be inexpensive to manufacture, and which will be reliable in operation.

Another object is to provide such a device which may be used as an overload switch, or as a thermostat, or both.

Another object i to provide such a device which is frictionless in operation and is unaflected by dust or humidity.

Another object is to provide a switch device of the character described which may be readily manufactured in normally open, normally closed, automatically recycling, or non-recycling, types.

Other objects and advantages of the invention will hereinafter appear.

The accompanying drawings illustrate certain embodiments of the invention which will now be described, it being understood that certain modifications in respect of structural details may be made in the embodiments illustrated without departing from the spirit or scope of the invention as defined by the appended claims.

In the drawings, Figure 1 is a cross sectional view of a diaphragm member;

Fig. 2 is a top plan view of the member shown in Fig. 1;

Fig. 3 i a view in cross section of a switch device embodying the invention;

Fig. 4 is a view in cross section of a modified form of the device shown in Fig. 3;

Fig. 5 is a view in cross section of an alternative form of a switch device embodying the invention; and,

Fig. 6 is a fragmentary cross sectional view of an alternative form of switch contacts.

Referring to Figs. 1 to 4, inclusive, of the drawings, the numeral 10 generally designates a diaphragm member which may be die-formed or stamped from a suitable metal blank. Member 10 is provided with a substantially circular bulge 14, the central or diaphragm portion 16 of which is re-entrant with respect to the bulge. In this embodiment the central portion 16 is normally disposed or biased so that the apex 18 thereof normally extends beyond the plane of the periphery of the bulge 14. One side of member 19, as shown, may be provided with an extension having therein a perforation 12 adapted to facilitate connection of the member in an electric circuit.

When member 10 is attached at a peripheral portion or ring 20 about its bulge portion 14 to a substantially rigid or inflexible metal plate 22, as shown in Fig. 3, the apex 18 will normally engage the plate. The central portion or diaphragm 16 will thus be displaced, and by its resilience will normally cause apex 18 to engage plate 22 with a predetermined degree of pressure to afford a good electrical connection therebetween. Member 10 is 2,798,130 Patented July 2, 1957 secured to plate 22 by an insulating and sealing material 24, hereinafter more fully described, to provide a sealed unit, and the same is normally electrically insulated from plate 22 except at apex 18.

The unit is filled with a suitable fluid 25 such as a vapor which at some critical temperature, and consequent pressure thereof, causes the diaphragm 16 to move outwardly from its relative re-entrant position in the bulge. This motion is similar to the action of an oil can and occurs with a snap movement. Apex 18 is held in firm electrical contact with plate 22 until withdrawn therefrom with a snap action by the diaphragm 16.

An electric current flowing between member 10 and plate 22 through apex 18 will heat member 10 and plate 22 and the fluid 25 therebetween. At some critical temperature caused by the flow of excessive current resulting from an overload or the like, the diaphragm 16 of member 10 will snap outwardly to break the contact between apex 18 and plate 22 and thereby interrupt the circuit. The diaphragm 16 would then assume a shape somewhat like that of diaphragm 16 in Fig. 4 which illustrates a normally open switch device as hereinafter more fully described. When applicable, the diaphragm member 10 may be connected in series in one electrical circuit and the plate may be connected in series in another. The circuits will be interconnected through apex 18 until a critical temperature and/ or pressure is reached.

By the use of design methods well known in the art the normal disposition or biasing of diaphragm 16 may be made such that as the fluid cools the diaphragm 16 will return to its normal position to effect reclosure of the switch. Or the biasing may be made sufiiciently extreme so that additional external force is required to return the diaphragm 16 to its switch-closed position.

In addition to acting as a thermally responsive overload switch, the device will act as a thermostat responsive to the temperature of the atmosphere and/ or objects surrounding it. The diaphragm 16 (see Fig. 4) is normally disposed or biased in such manner that instead of being normally re-entrant with respect to the bulge 14 it normally extends outwardly of the bulge to provide a normally open switch. Except for this difference the switch device of Fig. 4 may be like that shown in Fig. 3. Upon the reduction of the fluid pressure to some preselected value the diaphragm 16* will snap inwardly in a re-entrant relationship to the bulge 14?. Contact will be effected and maintained between apex 18 and plate 22 until the fluid pressure increases sufliciently to permit snapping of the diaphragm 16 back to its normal position.

Although in Figs. 1 to 4, inclusive, apices 18 and 18 and plates 22 and 22 are shown as adapted to engage one another directly, it may be preferable for certain applications of these switches to provide either or both of their respective apices and plates with a contact member such as contact tips 26, 26 illustrated in Fig. 5. This figure shows a switch unit which contains a fluid 29 and comprises two like diaphragm members 30, 30 secured together, as shown, at their respective peripheral or ring portions 34, 34 through the medium of a suitable insulating and sealing material 33. Contact tips 26, 26 are secured to the alined apices 40, 40 of the respective central portions of diaphragm members 30, 30. These diaphragm members 30, 31 may, like member 10, be normally disposed or biased to provide for automatic or non-recycling action, and for normally closed or for normally open positioning of the switch contacts 26, 26. Moreover, said device may be used either as a thermostat or as an overload switch, as desired.

It will be apparent to those familiar with the art that the plates 22 and 22 and the respective diaphragm members need not have the particular shapes, illustrated in the drawings. Other shapes of diaphragms might be utilized to provide an action similar to the action described, and such diaphragrns might be normally disposed or biased by well knownprocedures to provide the various modes of operation above set forth.

The body of material (24, 2'4 and 38) may be of any suitable insulating and sealing material. Vitreous enamel may be used, especially if the diaphragm members and plates are made of enameling steel, or stainless steel. Pulverized glass may be used with nickel-copper alloys; and pulverized borosilicate glass is satisfactory when used with beryllium-copper alloys. Said insulating and sealing material is fired to provide astrong bond between the same and the metal parts.

The units may be filled with fluid at a suitable pressure by assembling them in an atmosphere of water vapor, for example, or other suitable fluid, which fluid is maintained at the proper ambient pressure and temperature. To prevent arcing at the contacts when the pressure of the fluid is just below that value required to effect snap action of the diaphragm, one or both contacts may be resiliently mounted as on bowed springs or on cantilever springs, as illustrated in Fig. 6. The contact tips 48, 48, in Fig. 6, are mounted at one end of cantilever springs 46, 46, respectively. Said springs are attached at their opposite ends 50, 50 to an associated one of diaphragms 3'0, 30. Alternatively, the springs 46, 46 may themselves be utilized as the switch contacts.

I claim:

1. An electric switch comprising a first and a second conductive diaphragm member, each of said members having a diaphragm biased for snap action movement thereof, an insulating material interposed between a peripheral portion of said first member and a peripheral portion of said second member to form a sealed unit, a body or fiuid sealed between said members and adapted upon the attainment of a preselected pressure to effect snap action of at least one of said diaphragms from one position to another position, each of said diaphragms having a central portion for engagement with the central portion of the other in one of said positions of said diaphragms and for disengagement therefrom in the other of said positions of at least one of said diaphragms.

2. An electric switch of the character defined by claim 1 in which said insulating material comprises vitreous enamel.

3. An electric switch comprising, aconductive diaphragm member having, a diaphragm portion biased for snap action thereof in response to a pressure, a conductive member underlying said diaphragm, an insulating material interposed between said conductive member and a peripheral portion of said diaphragm member to form a sealed unit, a body of fluid disposed within y said unit, and a contactinterposed between said diaphragm and said conductive member and fastened to one of the same for effecting electrical connection therebetween.

4. An electric switch comprising, a conductive diaphragm member having a diaphragm portion biased for snap action thereof in response to a pressure, a conductive member underlyingsaid diaphragm, an insulating material interposed between said conductive memher and a peripheral portion of said diaphragm member to form a sealed unit, and a body of fluid disposed within'the said unit; said diaphragm having a central portion biased for normal engagement of said central portion with said conductive member.

5. An electric switch comprising a conductive disc member having a diaphragm portion movable with a snap action in response to a predetermined amount of pressure difference thereacross, a conductive member underlying said disc member, insulating material interposed between said conductive member and a peripheral portion of said disc member to form a sealed unit, and

a body of fluid within said unit varying the internal pressure thereof in accordance with its temperature, said diaphragm portion of said disc member having a central portion normally biased to engage said conductive member when the pressure difierence thereacross is less than said predetermined amount.

ReferencesCited in the-file of this patent UNITED STATES PATENTS 

